AS a new Cape Dory owner, I noticed some rust at the connection of the pintle and rudder. Is this common and what is the most effective way to rectify?
craig@ullers.com
pintle/rudder rust
Moderator: Jim Walsh
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len
Re: pintle/rudder rust
craig
i had to pull my rudder this winter to fix the pintle/gudgeon system so i can tell you how it is constructed which may help you decide what to do - the gudgeon is built in to the bottom of th rudder - it is a bronze or naval brass cylinder that is glassed in - the pintle is a stainless post in a bronze shoe - the shoe is held on the keel with bronze pins and then glassed over - the stainless post is supposed to be firmly fixed to the shoe and the gudgeon rotates around it - mine became totally loose and the gudgeon became elliptical, hence the necessity of repair
if there is rust, there must be some electrolytic action going on affecting the stainless post - others hopefully will have ideas about what to do about it - personally, if the bottom of the rudder has no play in it when you push on it (pushing directly from the stern towards the bow), i would clean it up as best i could and check it each year until it had to be fixed -
len
md.frel@nwh.org
i had to pull my rudder this winter to fix the pintle/gudgeon system so i can tell you how it is constructed which may help you decide what to do - the gudgeon is built in to the bottom of th rudder - it is a bronze or naval brass cylinder that is glassed in - the pintle is a stainless post in a bronze shoe - the shoe is held on the keel with bronze pins and then glassed over - the stainless post is supposed to be firmly fixed to the shoe and the gudgeon rotates around it - mine became totally loose and the gudgeon became elliptical, hence the necessity of repair
if there is rust, there must be some electrolytic action going on affecting the stainless post - others hopefully will have ideas about what to do about it - personally, if the bottom of the rudder has no play in it when you push on it (pushing directly from the stern towards the bow), i would clean it up as best i could and check it each year until it had to be fixed -
len
md.frel@nwh.org
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Bristol Bronze
Re: pintle/rudder rust
For the Information of All HandsCraig wrote: AS a new Cape Dory owner, I noticed some rust at the connection of the pintle and rudder. Is this common and what is the most effective way to rectify?
Bronze and stainless steel are dis-similar metals. Since stainless steel is lower on the nobility table than Bronze the stainless will become a sacrificial annode and start to lose electrons. If the reaction goes on long enough the lower nobility metal will corrode away.
Stainless steel gets it atmospheric corrosion resistance from a layer of oxide that builds up on its surface. This oxide requires a constant supply of oxygen to maintain itself. Under water this oxygen is supplied by the free flowing water around the stainless steel part. If the stainless steel is in a protected area (like a pintal inside a gudgeon) where the water is not always free flowing, then the oxide will use up all of the available oxygen from the surrounding water. The protective oxide will break down and the stainless steel will begin to rust. Very few modern boat manufacturers are metalurgicaly knowledgeable and this type of problem occurs frequently. Stainless steel should not be used under water and definately not in contact with a more noble metal.
A boat owner with this problem does not have to run about screaming that "the sky is falling" but at some point in the future should plan to replace the stainless steel pin with a good Bronze one. Since this can be a bit of work it probably should not be done until the corrosion becomes objectionable.
Roger W.
Bristol Bronze
401-625-5224
rogerw@meganet.net